What are the side effects of L-Lysine?

Potential side effects include: Gastrointestinal discomfort (nausea, diarrhea), Abdominal cramps at high doses, Potential kidney stress in individuals with renal impairment.

Is L-lysine effective for hair loss?

L-lysine is an essential amino acid that may support iron and zinc absorption — two minerals critical for hair growth. Research suggests that L-lysine supplementation alongside iron may improve ferritin levels more effectively than iron alone in women with chronic telogen effluvium. L-lysine also plays a role in collagen formation. Most studies use 1,500 mg/day. Consult your healthcare provider.

How does L-lysine support iron absorption and why does that matter for hair?

L-lysine is thought to enhance non-heme iron absorption by facilitating its transport across intestinal cells — an effect demonstrated in a study where women with chronic telogen effluvium experienced significantly greater ferritin increases when L-lysine (1,500 mg) was added to their iron supplementation compared to iron alone. Ferritin (stored iron) is a key biomarker for hair health; levels below 30–40 ng/mL are associated with increased shedding even without overt anemia. This lysine-iron synergy makes L-lysine particularly relevant for women with hair thinning and borderline iron stores. A ferritin test can help determine whether iron-related hair loss may be a factor.

What food sources provide L-lysine and when might supplementation be needed?

L-lysine is found abundantly in animal proteins — meat, poultry, fish, eggs, and dairy provide the highest concentrations, with a 3-oz serving of chicken supplying roughly 2,500 mg. Plant-based sources include legumes, especially lentils and chickpeas, though plant-protein diets may provide lower total lysine. People following vegan or restrictive diets, or those with high protein requirements, may benefit most from L-lysine supplementation. Research suggests supplementation makes the most practical difference for hair health when ferritin is low and dietary lysine intake is suboptimal. Typical supplemental doses of 500–1,500 mg daily are well tolerated in most people.

L-Lysine

amino-acid

Also known as: Lysine, L-Lysine HCl

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About

L-Lysine is an essential amino acid that may support hair health by enhancing iron and zinc absorption — two minerals critical for normal hair cycling. Research suggests lysine supplementation may be particularly beneficial for individuals with iron-deficiency-related hair shedding, especially when combined with iron supplementation.

How It Works

Enhances intestinal iron and zinc absorption; serves as a building block for keratin protein synthesis; may modulate 5-alpha-reductase activity.

Evidence For Conditions

Condition	Grade	Studies	Participants
Telogen Effluvium	D	1	--	View →
Iron Deficiency Hair Loss	D	1	--	View →

Side Effects

Gastrointestinal discomfort (nausea, diarrhea)
Abdominal cramps at high doses
Potential kidney stress in individuals with renal impairment

Drug & Supplement Interactions

Calcium supplements (lysine increases calcium absorption — may require monitoring)
Aminoglycoside antibiotics (potential for increased nephrotoxicity)
Iron supplements (synergistic — may enhance iron absorption)

Always inform your healthcare provider about all supplements you take.

Quick Facts

Dosage: General: 500-1,500 mg/day
Forms: capsule tablet powder
Natural Sources: Red meat, Poultry, Fish, Eggs, Soybeans, Cheese
Upper Limit: Not formally established; 3,000 mg/day considered safe in studies
Best Time: On an empty stomach or with iron supplements for enhanced absorption

Evidence Summary

Telogen Effluvium D

Iron Deficiency Hair Loss D

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.